Not Applicable.
The invention relates generally to an improved vehicle truck seat assembly that provides support and shock dampening to the ischial area of the driver as well as front-to-back and lateral stabilization. The seat assembly employs an inflatable air cell cushion with a central inflation zone comprised of individual inflation cells interconnected by an airflow path that provide optimum shock absorption qualities. Bolster zones comprised of individual air cells surround the central inflation zone. The inflation cells have a cell geometry that allows for improved molding of a support cushion comprised of individual fluted or finned cells.
Truck drivers seated for long periods of time in the cab of a truck can suffer discomfort caused by pressure, road shock and vibration. It has been shown that persons who are required to stay seated for long periods of time, for example, long haul truck drivers, experience muscle fatigue, loss of flexibility and back pain, particularly due to truck vibrations transmitted to the driver. Any driver discomfort, soreness or numbness in the buttocks and legs, can be attributed to a loss of blood flow in the tissue from unrelieved pressure on the skin. Besides creating physiological problems, this discomfort may require the driver to make frequent stops or shorter trips, decreasing efficiency.
Inflatable cellular cushions provide the most uniform distribution of weight and thus provide the greatest protection from seating pressure. These cushions have an array of closely spaced air cells that project upwardly from a common base. Within the base the air cells communicate with each other, and thus, all exist at the same internal pressure. Hence, each air cell exerts essentially the same restoring force against the buttocks, irrespective of the extent to which it is deflected. U.S. Pat. No. 4,541,136 shows a cellular cushion for use on wheelchairs.
U.S. Pat. No. 3,870,450 illustrates another cushion design and discloses a conventional method and apparatus for molding and assembling the cushions. U.S. Pat. No. 3,870,450 and U.S. Pat. No. 4,005,236 disclose fluted cells. The cells are spaced apart to prevent material that is in the soft or uncured condition from the dipping process from bridging adjacent cells during forming. U.S. Pat. No. 4,541,136 provides a multicell cushion in which the individual cells have a finned configuration when deflated. This cell configuration allows the cells to contact each other along their sides when inflated to provide a continuous supporting surface.
Generally fluted or finned cells have a higher profile than vacuum molding will allow. That is, to vacuum mold, you would pull the material into the mold to fill out the form stretching it and causing it to thin out and become weak. The thin areas cool off too quickly and can break. This can be avoided with dip molding. Due to the cost, dip-molding methods generally are used to make cushions having individual cells of identical configurations and support characteristics.
Heretofore, molded inflatable air cell cushion technology has been directed to medical uses, such as wheelchair cushions or mattress overlays for compromised patients, and has not been optimally employed in seating for vehicles, such as trucks. Although such cellular cushions work well for preventing pressure sores, they have not necessarily addressed the problems associated with able-bodied vehicle drivers, such as vibration and shock to the ischial area and front-to-back and side-to-side stabilization.
It would be advantageous, therefore, to provide vehicular seating that addresses the problems of pressure, vibration, road shock and stabilization utilizing inflatable air cell technology. It also would be advantageous to develop a vehicular seating assembly incorporating an improved inflatable cellular cushions which can be installed in the vehicle and controlled by the driver that improves seating comfort for these drivers.
It also would be advantageous to vacuum mold plastics to form finned cushion cells. Labor costs are less for vacuum molding. Vacuum molding would allow a manufacturer to make cushions having varied finned cell configurations and arrangements. Thus, cushions could be custom made to fit the anatomy of individual truck drivers.
One aspect of the invention is a seat assembly for a vehicle having enhanced vibration and shock absorption characteristics.
Another aspect of the invention is a seat assembly for a vehicle having enhanced front-to-back and side-to-side stabilization characteristics.
Another aspect of the invention is an improved cushion for use in a vehicle that provides improved seating comfort for the user, particularly drivers who sit for extended periods of time, such as over-the-road truck drivers.
Another aspect of this invention is an improved cushion cell geometry that allows for vacuum molding a finned cushion from urethane or other plastic.
According to the invention, briefly stated, an improved truck seat assembly incorporating an improved inflatable air cell cushion is provided. The inflatable air cushion includes a plurality of inflation zones comprised of individual cells. For example, one such cushion includes five zones. One zone of cells is located approximately at the middle of the cushion to be positioned under the ischial area of the driver. There are four zones comprised around the perimeter of the cushion to function as bolsters. The cushion can be mounted on a relatively solid base or a foam base that can be attached to a seat support plate. A flexible plastic seat support plate allows the truck seat pan to dampen truck vibrations and shock loads. mounted on the frame of the original truck seat. The support, the base and the air cell cushion provide desired road vibration absorption characteristics. In another embodiment, a support fabric supports the base and the air cell cushion. The tension on the fabric can be adjusted to obtain optimal support and vibration dampening characteristics.
The peripheral zones are connected by valve and air lines through an air regulator to the truck""s air supply system to control air pressure in the peripheral zones. The driver can adjust the pressure in the peripheral zones for seating comfort and lateral support or the cushion can be completely automatic and fit to the driver. The air regulator is pre-set to provide optimal pressure to the ischial zone.
In another embodiment of the invention sensors, such as a bottom out sensor or xe2x80x9csmart fabricxe2x80x9d is used to cover the cushion. The xe2x80x9csmart fabricxe2x80x9d is used to determine pressures in various and, through a feedback loop to the air supply, adjust the air pressure.
Also provided is an improved cushion with individual inflation cells having an improved cell geometry that provides optimal support characteristics with manufacturing advantages. The novel cell has an optimum ratio of area of the cell to area of the base (footprint) is 3:1 which allows for vacuum molding. For example, in one embodiment the cushion cell has a 2.5-inch by 2.5-inch (6.25 square inch) base or footprint and a surface area of 18.75 square inches or less. Vacuum molding is less expensive than dip molding and, therefore, making it commercially and economically feasible to provide multiple variations of cushion configurations.